There is a need for voltage measurement in high voltage electric power systems for monitoring, protection, metering and other “smart grid” operations. Conventional high voltage sensors are relatively large and heavy. This makes them impractical to implement on phase-over-phase poles and other distribution circuits where weight is a critical factor. While certain types of light weight high voltage sensors are available, they are severely affected by stray capacitance caused by other structures, such as adjacent voltage sources. The sensor accuracy is further degraded by environmental contamination such as rain, crud accumulation, changes in temperature and pollution resulting in unpredictable errors that vary with weather accumulated crud conditions. These factors negatively impact the accuracy below the requirements for most applications.
Still other voltage measurement systems, such as piezoelectric transformer (PT) based technologies and other designs utilizing component housed within dielectric canisters, require the high voltage conductor carrying the line current to pass through the interior of the housing. While this minimizes environmental contamination such as crus accumulation, it also requires a relatively large diameter housing surrounding the line conductor. Alternative approaches designed to mitigate environmental factors utilize complex and expensive “pockels” type fiber optic sensors. These approaches do meet the need for light weight, small, inexpensive voltage sensors. As a result, there is continuing need for improved high voltage sensors for electric power lines.